Resin composition, liquid composition, laminate, and method for removing printed layer

Abstract

Provided is a resin composition for preparing liquid compositions such as inks with excellent fluidity, which can form a printing layer that has excellent blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali release property on a substrate made of A-PET, HDPE, LLDPE, or the like while suppressing whitening of the substrate. [Solution] This resin composition is used in a liquid composition for forming a removable printing layer on a substrate made of a resin such as A-PET. It contains a (meth)acrylic resin (A) with an acid value of less than 25 mgKOH / g, a styrene-(meth)acrylic resin (B) with an acid value of 25 to 90 mgKOH / g, and a dispersing resin (C) with an acid value of 150 to 400 mgKOH / g, in which the total content of the styrene-(meth)acrylic resin (B) and the dispersing resin (C) is 10 to 30 mass% of the solid content of the resin composition, and the content of the dispersing resin (C) per part by mass of the styrene-(meth)acrylic resin (B) is 0.1 to 1.5 mass parts.

Description

[Technical Field]

[0001] The present invention relates to a resin composition, a liquid composition, a laminate, and a method for removing a printed layer. [Background technology]

[0002] Due to the excellent properties of plastics, plastic products, such as various containers and packaging materials, are widely used around the world, especially in the food industry. Plastic products are indispensable in modern life because they are light, durable, and easy to mass-produce. For example, amorphous polyethylene terephthalate (A-PET) is a plastic that is glossy, highly transparent, and easily molded. Taking advantage of these properties, A-PET is widely used as a component material for products such as containers and packaging materials for foods such as salads, side dishes, sushi, and sashimi. High-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) are also widely used as components for products such as garbage bags and rice bags.

[0003] On the surface of various products made of plastic materials, various information such as the product name, contents, and manufacturer is usually printed directly with ink, or a resin label with various information printed on it is affixed. Also, on the surface of resin bags for storing bread, rice balls, prepared foods, etc., various information such as the product name is usually printed with ink.

[0004] From the viewpoint of protecting the global environment, various molded articles (substrates) such as containers, labels, and bags are collected, recycled, and widely used as secondary products. However, as mentioned above, various information is printed on the surface of these substrates with ink. Therefore, when recycling and reusing resin molded articles and labels, it is necessary to remove the ink applied to their surfaces beforehand.

[0005] Various methods have been proposed to recycle plastic substrates by removing ink printed on them through detachment. For example, methods for producing packaging materials and recycled molding materials with excellent detachment properties from printed substrates have been proposed (Patent Documents 1 and 3). Also proposed is an organic solvent-based ink containing a urethane resin with acidic groups at its terminals for forming a detachment layer for peeling a plastic film from a laminate (Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2023-036097 [Patent Document 2] Japanese Patent Publication No. 2023-88345 [Patent Document 3] Patent No. 7546182 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the printed layers formed using the conventional inks proposed in Patent Documents 1 and 2 etc. did not necessarily have good adhesion to substrates made of polyester resins such as A-PET or polyolefin resins such as polyethylene, or good releasability from these substrates by alkali treatment. Furthermore, the properties of the detachable printed layers formed using the conventional inks etc., such as blocking resistance, abrasion resistance, and heat resistance, were not necessarily sufficient, and further improvements were desired.

[0008] The present invention has been made in view of the problems associated with the prior art, and an object of the present invention is to provide a resin composition for preparing a liquid composition such as an ink that can form a printing layer having excellent storage stability (fluidity), blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali release property on a substrate made of amorphous polyethylene terephthalate, high-density polyethylene, linear low-density polyethylene, or the like, while suppressing whitening of the substrate.

[0009] Another object of the present invention is to provide a liquid composition such as an ink that can form a printed layer having excellent storage stability (fluidity), blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali release property on a substrate made of amorphous polyethylene terephthalate, high-density polyethylene, linear low-density polyethylene, etc., while suppressing whitening of the substrate. Another object of the present invention is to provide a removable printed layer formed from the above liquid composition, a laminate including this removable printed layer, and a method for removing the printed layer from this laminate. [Means for solving the problem]

[0010] That is, according to the present invention, there is provided the following resin composition. [1] A resin composition used in a liquid composition for forming a removable printing layer on a substrate formed of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene, comprising: a (meth)acrylic resin (A) having an acid value of less than 25 mgKOH / g; a styrene-(meth)acrylic resin (B) having an acid value of 25 to 90 mgKOH / g; and a dispersing resin (C) having an acid value of 150 to 400 mgKOH / g, wherein the total content of the styrene-(meth)acrylic resin (B) and the dispersing resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 10 to 30 mass %. %, the content of the dispersing resin (C) relative to 1 part by mass of the styrene-(meth)acrylic resin (B) is 0.1 to 1.5 parts by mass, the total content of the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B) and the dispersing resin (C) in the solid content of the liquid composition (excluding colorants such as pigments) is 65 to 100% by mass, the liquid composition contains a solvent including an alcohol-based solvent and an ester-based solvent, the total content of the alcohol-based solvent and the ester-based solvent in the solvent is 90 to 100% by mass, and the mass ratio of the alcohol-based solvent to the ester-based solvent is 2.5:7.5 to 7:3. [2] The resin composition according to [1], wherein the (meth)acrylic resin (A) has a glass transition temperature of 40 to 65°C. [3] The resin composition according to [1] or [2], wherein the content of the (meth)acrylic resin (A) in the solid content of the liquid composition (excluding colorants such as pigments) is 40 to 75 mass %. [4] The resin composition according to any one of [1] to [3], wherein the dispersing resin (C) is at least one selected from the group consisting of carboxylic acid-based resins and ammonium salt-based resins. [5] The resin composition according to any one of [1] to [4] above, further comprising silica having an average particle size of 1.0 to 8.0 μm. [6] The resin composition according to any one of [1] to [5] above, further comprising a cellulose resin.

[0011] The present invention also provides the following liquid composition. [7] A liquid composition for forming a removable printing layer on a substrate formed of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene, comprising a solvent containing an alcohol-based solvent and an ester-based solvent, a printing composition for forming a non-detachable printing layer, and a resin composition described in any of [1] to [6] above, wherein the total content of the alcohol-based solvent and the ester-based solvent in the solvent is 90 to 100 mass %, and the mass ratio of the alcohol-based solvent to the ester-based solvent is 2.5:7.5 to 7:3. [8] A liquid composition for forming a removable printing layer on a substrate formed of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene, comprising: a (meth)acrylic resin (A) having an acid value of less than 25 mgKOH / g; a styrene-(meth)acrylic resin (B) having an acid value of 25 to 90 mgKOH / g; a dispersion resin (C) having an acid value of 150 to 400 mgKOH / g; and a solvent including an alcohol-based solvent and an ester-based solvent; wherein the styrene-(meth)acrylic resin (B) is a styrene-(meth)acrylic resin having an acid value of 25 to 90 mgKOH / g; a dispersion resin (C) having an acid value of 150 to 400 mgKOH / g; and a solvent including an alcohol-based solvent and an ester-based solvent; a total content of the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B) and the dispersing resin (C) is 10 to 30 mass %, a content of the dispersing resin (C) relative to 1 mass part of the styrene-(meth)acrylic resin (B) is 0.1 to 1.5 mass parts, a total content of the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B) and the dispersing resin (C) in the solid content of the liquid composition (excluding colorants such as pigments) is 65 to 100 mass %, a total content of the alcohol-based solvent and the ester-based solvent in the solvent is 90 to 100 mass %, and a mass ratio of the alcohol-based solvent to the ester-based solvent is 2.5:7.5 to 7:3. [9] The liquid composition according to [7] or [8], wherein the alcohol-based solvent is at least one selected from the group consisting of isopropyl alcohol, methanol, ethanol, n-propanol, and n-butanol.

[10] The liquid composition according to any one of [7] to [9], wherein the ester-based solvent is at least one selected from the group consisting of ethyl acetate, propyl acetate, and butyl acetate.

[11] A liquid composition according to any one of [7] to

[10] , wherein when cellophane tape is applied to a portion of the surface of a printed layer formed by applying the liquid composition to the substrate and then quickly peeled off, the ratio of the area of ​​the peeled printed layer to the adhesive area of ​​the cellophane tape is less than 20%.

[0012] Furthermore, according to the present invention, the use of the liquid composition as described below in inks and the like, and the inks and the like are provided.

[12] Use of the liquid composition according to any one of the above [7] to

[11] in a medium, a primer, an overcoat varnish, or an ink containing a coloring material.

[13] A medium, primer, overcoat varnish, or ink containing a coloring material, which is obtained by using the liquid composition according to any one of [7] to

[11] above.

[0013] The present invention also provides the following removable printing layer and laminate.

[14] A removable printing layer formed from the medium, primer, overcoat varnish, or ink containing a colorant described in

[13] above, placed on a substrate formed from at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene.

[15] A laminate comprising a substrate formed of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene, and a removable printed layer described in

[14] placed on the substrate.

[16] The laminate according to

[15] above, which is a container or a lid material.

[0014] Furthermore, according to the present invention, there is provided a method for removing a printed layer, as described below.

[17] A method for removing a printed layer, comprising the step of contacting the printed layer of the laminate described in

[15] or

[16] with an alkaline aqueous solution to remove and detach the printed layer from the substrate.

[18] The method for removing a printed layer according to

[17] , further comprising the step of recovering the substrate from which the printed layer has been removed. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a resin composition for preparing a liquid composition such as an ink that can form a printing layer having excellent storage stability (fluidity), blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali release property on a substrate made of amorphous polyethylene terephthalate, high-density polyethylene, linear low-density polyethylene, or the like while suppressing whitening of the substrate.

[0016] The present invention also provides a liquid composition such as an ink that can form a printed layer having excellent storage stability (fluidity), blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali release property on a substrate made of amorphous polyethylene terephthalate, high-density polyethylene, linear low-density polyethylene, etc., while suppressing whitening of the substrate. Furthermore, the present invention can provide a removable printed layer formed from the above liquid composition, a laminate including this removable printed layer, and a method for removing the printed layer from this laminate. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present inventors have investigated resin compositions for preparing liquid compositions capable of forming printed layers having excellent storage stability, blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali release properties on the surfaces of various molded articles (substrates) made of amorphous polyethylene terephthalate (A-PET), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE) while suppressing whitening of the substrate. Furthermore, they have investigated liquid compositions capable of forming printed layers having excellent storage stability, blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali release properties on substrates made of amorphous polyethylene terephthalate, high-density polyethylene, linear low-density polyethylene, and the like while suppressing whitening of the substrate. As a result, it was discovered that when a liquid composition containing a (meth)acrylic resin, a styrene-(meth)acrylic resin, and a dispersion resin, each having an acid value within a certain range, and used in a liquid composition containing an alcohol-based solvent and an ester-based solvent in a predetermined quantitative ratio, is prepared and used on the surface of the substrate, it is possible to form a printed layer with improved properties such as storage stability, adhesion, alkali release, blocking resistance, abrasion resistance, and heat resistance, without whitening the substrate, and this led to the present invention.

[0018] <Resin composition> One embodiment of the resin composition of the present invention is a liquid composition for forming a removable printing layer on a substrate formed of at least one resin selected from the group consisting of amorphous polyethylene terephthalate (A-PET), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE). The resin composition contains a (meth)acrylic resin (A) having an acid value of less than 25 mgKOH / g, a styrene-(meth)acrylic resin (B) having an acid value of 25 to 90 mgKOH / g, and a dispersing resin (C) having an acid value of 150 to 400 mgKOH / g. The total content of the styrene-(meth)acrylic resin (B) and the dispersing resin (C) in the solids content (excluding colorants such as pigments) of the liquid composition is 10 to 30% by mass, and the content of the dispersing resin (C) per part by mass of the styrene-(meth)acrylic resin (B) is 0.1 to 1.5 parts by mass. The total content of the (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) in the solid content of the liquid composition (excluding colorants such as pigments) is 65 to 100 mass%. The liquid composition prepared using the resin composition of this embodiment contains a solvent including an alcohol-based solvent and an ester-based solvent, and the total content of the alcohol-based solvent and the ester-based solvent in the solvent is 90 to 100 mass%, and the mass ratio of the alcohol-based solvent to the ester-based solvent is 2.5:7.5 to 7:3. The resin composition of this embodiment will be described in detail below.

[0019] ((Meth)acrylic resin (A)) The (meth)acrylic resin (A) is a component used for the purpose of improving the properties of the printing layer, such as blocking resistance, adhesion, abrasion resistance, and heat resistance. The (meth)acrylic resin (A) is a resin (polymer) whose main component is a structural unit derived from (meth)acrylate ((meth)acrylic acid ester). Examples of the (meth)acrylic resin (A) include a homopolymer of (meth)acrylate; a copolymer of multiple types of (meth)acrylate; and a copolymer of (meth)acrylate and another polymerizable monomer copolymerizable with (meth)acrylate. In this specification, "(meth)acrylic" means both "acrylic" and "methacrylic." The content of the structural unit derived from (meth)acrylate in the (meth)acrylic resin (A) is preferably 10 to 100% by mass, more preferably 20 to 100% by mass.

[0020] Examples of (meth)acrylates include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate; cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate; aryl (meth)acrylates such as phenyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; and hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0021] Examples of other polymerizable monomers copolymerizable with (meth)acrylates include conjugated diene compounds such as 1,3-butadiene, isoprene, and chloroprene; aromatic vinyl compounds such as styrene, α-methylstyrene, halogenated styrene, and divinylbenzene; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; acrylamides such as N,N-dimethyl(meth)acrylamide and N,N-diethyl(meth)acrylamide; unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, maleic acid, and fumaric acid; and unsaturated carboxylic acid esters such as diethyl maleate, dibutyl maleate, dibutyl fumarate, diethyl itaconate, and dibutyl itaconate.

[0022] The acid value of the (meth)acrylic resin (A) is less than 25 mgKOH / g, preferably 0 to 18 mgKOH / g, and more preferably 0 to 12 mgKOH / g from the viewpoint of adhesion and heat resistance. The acid value of the (meth)acrylic resin (A) may be 0. By setting the acid value of the (meth)acrylic resin (A) within the above range, the adhesion of the printed layer to the substrate and heat resistance can be improved. If the acid value of the (meth)acrylic resin (A) is 25 mgKOH / g or more, the adhesion and water resistance of the printed layer formed on the substrate made of A-PET and LLDPE will be insufficient. The acid value in this specification is a value measured by neutralization titration method in accordance with JIS K 0070-1992.

[0023] The glass transition temperature of the (meth)acrylic resin (A) is preferably 40 to 65° C., more preferably 40 to 62° C. By adjusting the glass transition temperature of the (meth)acrylic resin (A) to be within the above range, the blocking resistance of the printed layer and the adhesion to the substrate can be further improved.

[0024] The weight-average molecular weight of the (meth)acrylic resin (A) is preferably 1,000 to 1,000,000, and more preferably 5,000 to 500,000. By setting the weight-average molecular weight of the (meth)acrylic resin (A) within the above range, it is possible to further improve storage stability, blocking resistance of the printed layer, and adhesion to the substrate. From the viewpoint of improving the balance between storage stability, blocking resistance of the printed layer, and adhesion to the substrate, it is particularly preferable that the weight-average molecular weight of the (meth)acrylic resin (A) is 10,000 to 390,000.

[0025] The (meth)acrylic resin (A) can be obtained by polymerizing a monomer component containing a (meth)acrylate and, if necessary, other polymerizable monomers. Examples of the polymerization method include a method in which the monomer component is polymerized by a solution polymerization method, a bulk polymerization method, an emulsion polymerization method, or the like in the presence of a known radical polymerization initiator. The (meth)acrylic resin (A) may be a self-crosslinking resin.

[0026] As the (meth)acrylic resin (A), in addition to those produced according to conventional methods, commercially available products can be used. Commercially available resins that can be used as the (meth)acrylic resin (A) include, for example, the "Acrit" series manufactured by Taisei Fine Chemical Co., Ltd., and the "Hi-Loss-X TE-1048," "Hi-Loss-X NE-2186," "Hi-Loss-X KE-1062," "Hi-Loss-X QE-1042," "Hi-Loss-X X-436," "Hi-Loss-X KE-1060," "Hi-Loss-X HE-2342," "Hi-Loss-X HE-1335," "Hi-Loss-X RE-1075," "Hi-Loss-X PE-1304," "Hi-Loss-X KE-2536," "Hi-Loss-X J-140A," "Hi-Loss-X TE-1102," "Hi-Loss-X RE-218," "Hi-Loss-X NE-2009," "Hi-Loss-X JE-1056," "Hi-Loss-X KE-1148," and "Hi-Loss-X" manufactured by Seiko PMC Corporation. M-141," "Hi-Loss-X ME-2039," "Hi-Loss-X UE-1051," "Hi-Loss-X PE-1126," "Hi-Loss-X JE-1113," "Hi-Loss-X PL-1231," "Hi-Loss-X BL-2300," "Hi-Loss-X NL-1253," "Hi-Loss-X X-228L," "Hi-Loss-X M-30," "Hi-Loss-X UL-1191," "Hi-Loss-X YL-1098," "Hi-Loss-X QL-1358," "Hi-Loss-X YL-1825," "Hi-Loss-X X-345," "Hi-Loss-X GL-2439," "Hi-Loss-X VL-1147," "Hi-Loss-X X-321L," "Hi-Loss-X AW-36H," and "Hi-Loss-X NL-1189"; and products under the trade names "Ultrasol A-25" and "Ultrasol NL-1189" manufactured by AICA Corporation. A-35”, “Ultrasol A-40”, “Ultrasol A-50”, “Ultrasol C-63”, “Ultrasol C-70”, “Ultrasol D-32”, “Ultrasol D-40”, “Ultrasol GP-300”, and “Ultrasol UL-1097”;BASF Japan Ltd. trade names: "Joncryl PDX-7357," "Joncryl PDX-7182," "Joncryl PDX-7326," "Joncryl PDX-7616A," "Joncryl PDX-7732," "Joncryl PDX-7741," "Joncryl PDX-7787," "Joncryl PDX-7356," "Joncryl PDX-7734," "Joncryl PDX-7777," "Joncryl PDX-7615," "Joncryl PDX-7775," "Joncryl PDX-7692," "Joncryl PDX-7630A," "Joncryl PDX-7158," "Joncryl 352D," "Joncryl PDX-7199," "Joncryl PDX-7358," "Joncryl PDX-7667," "Joncryl PDX-7700," and "Joncryl PDX-7696" Examples include "Johncryl PDX-7780," "Johncryl PDX-7177," "Johncryl PDX-7164," "Johncryl PDX-7430," "Johncryl 67," "Johncryl 678," "Johncryl 611," "Johncryl 693," "Johncryl 682," "Johncryl 690," "Johncryl 819," "Johncryl JDX-C3000A," "Johncryl JDX-C3080," "Johncryl 52J," "Johncryl PDX-6157," "Johncryl 60J," "Johncryl 70J," "Johncryl JDX-6180," "Johncryl HPD-196," "Johncryl HPD-96J," "Johncryl PDX-6137A," "Johncryl 6610," "Johncryl JDX-6500," and "Johncryl PDX-6102B."

[0027] The content of the (meth)acrylic resin (A) in the solid content of the liquid composition (excluding colorants such as pigments) may be appropriately set depending on the intended use, etc. For example, the content of the (meth)acrylic resin (A) is preferably 40 to 75 mass %, more preferably 50 to 70 mass %, based on the solid content of the liquid composition, and particularly preferably 59 to 65 mass % from the viewpoint of achieving better blocking resistance, adhesion, and alkali release properties of the printed layer. By setting the content of the (meth)acrylic resin (A) within the above range, the blocking resistance, adhesion, and alkali release properties of the printed layer can be improved. If the content of the (meth)acrylic resin (A) is less than 40 mass %, the adhesion of the ink layer may be poor, and if it is more than 75 mass %, the alkali release properties and blocking resistance of the ink layer may be poor. However, in either case, the object of the present invention can be achieved.

[0028] The solid content of the (meth)acrylic resin (A) in the total mass of the liquid composition (excluding colorants such as pigments) may be appropriately set depending on the intended use, etc. For example, the solid content of the (meth)acrylic resin (A) is preferably 1 to 50 mass%, more preferably 3 to 35 mass%, based on the total mass of the liquid composition, and particularly preferably 5 to 20 mass% from the viewpoint of achieving better ink storage stability, blocking resistance, adhesion, and alkali release properties of the printed layer. By setting the solid content of the (meth)acrylic resin (A) within the above range, storage stability, and the blocking resistance, adhesion, and alkali release properties of the printed layer can be improved. If the solid content of the (meth)acrylic resin (A) is less than 1 mass%, the ink layer may have poor adhesion, and if it exceeds 50 mass%, the ink layer may have poor alkali release properties and blocking resistance. However, in either case, the object of the present invention can be achieved.

[0029] (Styrene-(meth)acrylic resin (B)) The styrene-(meth)acrylic resin (B) is a resin with a higher acid value than the (meth)acrylic resin (A). By using a (meth)acrylic resin (A) and a styrene-(meth)acrylic resin (B) in combination, which have different acid values, it is possible to impart alkali release properties while maintaining adhesion and heat resistance. The styrene-(meth)acrylic resin (B) is a resin (copolymer) having a structural unit derived from styrene and a structural unit derived from (meth)acrylate ((meth)acrylic acid ester). The styrene-(meth)acrylic resin (B) is similar to the above-mentioned (meth)acrylic resin (A) except that it has a structural unit derived from styrene as an essential structural unit and has a different acid value.

[0030] The acid value of the styrene-(meth)acrylic resin (B) is 25 to 90 mgKOH / g, preferably 26 to 90 mgKOH / g, more preferably 30 to 90 mgKOH / g, and particularly preferably 50 to 90 mgKOH / g from the viewpoint of further improving alkali release properties. By adjusting the acid value of the styrene-(meth)acrylic resin (B) within the above range, the adhesion and alkali release properties of the printed layer can be improved. If the acid value of the styrene-(meth)acrylic resin (B) is less than 25 mgKOH / g, the alkali release properties of the printed layer will be insufficient. On the other hand, if the acid value of the (meth)acrylic resin (B) is more than 80 mgKOH / g, the adhesion of the printed layer formed on a substrate made of HDPE and LLDPE will be insufficient.

[0031] The combined use of styrene-(meth)acrylic resin (B) and the dispersion resin (C) described below can further improve the alkali releasability of the printed layer. When printing on a substrate made of a polyester resin or polyolefin resin, such as a polyester resin substrate such as A-PET, these substrates have relatively low solvent resistance. Therefore, when a liquid composition such as a solvent-containing ink is applied, the substrate is slightly dissolved by the solvent to form a printed layer. Therefore, the printed layer formed adheres more firmly to the substrate than printed layers formed on substrates made of other resins. In other words, printed layers formed on substrates made of polyester resins such as A-PET or polyolefin resins typically tend to be more difficult to remove by alkali than printed layers formed on substrates made of other resins. In contrast, by using the resin composition or liquid composition of this embodiment, which combines styrene-(meth)acrylic resin (B) and dispersion resin (C), a printed layer with excellent alkali releasability can be formed, even when a substrate made of a polyester resin such as A-PET or polyolefin resin is used.

[0032] The styrene-(meth)acrylic resin (B) may be one produced by a conventional method or a commercially available product. Examples of commercially available resins that can be used as the styrene-(meth)acrylic resin (B) include the "Acrit" series manufactured by Taisei Fine Chemical Co., Ltd., and the "Hiros-X X-609" and "Hiros-X X-1" manufactured by Seiko PMC Corporation.

[0033] The content of the styrene-(meth)acrylic resin (B) in the solid content of the liquid composition (excluding colorants such as pigments) may be appropriately set depending on the intended use, etc. For example, the content of the styrene-(meth)acrylic resin (B) is preferably 4 to 28 mass %, more preferably 5 to 17 mass %, based on the solid content of the liquid composition, and particularly preferably 6 to 14 mass % from the viewpoint of achieving better blocking resistance and alkali release properties of the printed layer. By setting the content of the styrene-(meth)acrylic resin (B) within the above range, the blocking resistance and alkali release properties of the printed layer can be improved. If the content of the styrene-(meth)acrylic resin (B) is less than 4 mass %, alkali release properties may be poor, and if it is more than 28 mass %, blocking resistance may be poor. However, in either case, the object of the present invention can be achieved.

[0034] The solid content of the styrene-(meth)acrylic resin (B) in the total mass of the liquid composition (excluding colorants such as pigments) may be appropriately set depending on the intended use, etc. For example, the solid content of the styrene-(meth)acrylic resin (B) is preferably 0.1 to 10.0 mass%, more preferably 1.0 to 8.0 mass%, based on the total mass of the liquid composition, and particularly preferably 1.0 to 6.0 mass%, from the viewpoint of achieving better blocking resistance, alkali release properties, and water resistance of the printed layer. By setting the content of the styrene-(meth)acrylic resin (B) within the above range, storage stability and the blocking resistance and alkali release properties of the printed layer can be improved. If the solid content of the styrene-(meth)acrylic resin (B) is less than 0.1 mass%, alkali release properties may be poor, and if it exceeds 10.0 mass%, blocking resistance may be poor. However, in either case, the object of the present invention can be achieved.

[0035] (Dispersion resin (C)) The dispersing resin (C) is a resin other than the (meth)acrylic resin (A) and the styrene-(meth)acrylic resin (B), and is a component that contributes to improving the alkali release properties of the printed layer. Furthermore, when the liquid composition prepared using the resin composition of this embodiment contains a pigment component, the dispersing resin (C) is a component that can also function as a dispersant to improve dispersibility in the liquid medium. In other words, the use of the dispersing resin (C) can improve pigment dispersibility and also enhance the alkali release properties of the printed layer to be formed.

[0036] The acid value of the dispersing resin (C) is 150 to 400 mgKOH / g, preferably 170 to 390 mgKOH / g, and more preferably 200 to 380 mgKOH / g from the viewpoint of further improving alkali release properties and adhesion. By setting the acid value of the dispersing resin (C) within the above range, the alkali release properties, adhesion properties, and pigment dispersibility of the printed layer can be improved. If the acid value of the dispersing resin (C) is less than 150 mgKOH / g, the alkali release properties of the printed layer and adhesion properties between HDPE and LLDPE will be insufficient. On the other hand, if the acid value of the dispersing resin (C) is more than 400 mgKOH / g, the heat resistance and printability of the printed layer will be reduced.

[0037] As the dispersing resin (C), carboxylic acid resins, ammonium salt resins, phosphate ester resins, etc. can be used. Among them, carboxylic acid resins are more preferable as the dispersing resin (C) from the viewpoint of improving the affinity with the resin. Also, from the viewpoint of obtaining the same effect as that of the carboxylic acid resin, it is also a preferred embodiment to use an ammonium salt resin. Note that "carboxylic acid resin" means a resin having a carboxylic acid group (-COOH) in its molecule. Also, "ammonium salt resin" means a resin having an ammonium salt structure (-NH4) in its molecule. + X - (wherein "X" is a halogen atom)).

[0038] The dispersing resin (C) may be one produced by a conventional method or a commercially available product. Examples of commercially available resins that can be used as the dispersing resin (C) include those manufactured by BYK under the trade names "DISPERBYK-P104," "BYK-P105," and "DISPERBYK-102"; and those manufactured by Lubrizol under the trade names "Solsperse 45000," "Solsperse 17000," and "Solsperse 16000."

[0039] The content of the dispersion resin (C) in the solid content of the liquid composition (excluding colorants such as pigments) may be appropriately set depending on the intended use, etc. For example, the content of the dispersion resin (C) is preferably 0.9 to 18 mass %, more preferably 2 to 10 mass %, and particularly preferably 3 to 5.5 mass %, based on the solid content of the liquid composition (excluding colorants such as pigments). By keeping the content of the dispersion resin (C) within the above range, the storage stability, alkali release property, and heat resistance of the printed layer can be improved. If the content of the dispersion resin (C) is less than 0.9 mass %, the release property of the printed layer may be poor, and if it exceeds 18 mass %, the storage stability and heat resistance may be poor. However, in either case, the object of the present invention can be achieved.

[0040] The solid content of the dispersion resin (C) relative to the total mass of the liquid composition (excluding colorants such as pigments) may be appropriately determined depending on the intended use. For example, the solid content of the dispersion resin (C) is preferably 0.05 to 5.0 mass%, more preferably 0.1 to 4.0 mass%, based on the total mass of the liquid composition. From the viewpoint of achieving better storage stability, alkali releasability, and heat resistance of the printed layer, 0.15 to 3.0 mass% is particularly preferred. By setting the solid content of the dispersion resin (C) within the above range, the storage stability, alkali releasability, and heat resistance of the printed layer can be improved. If the solid content of the dispersion resin (C) is less than 0.05 mass%, the releasability of the printed layer may be poor, and if it exceeds 5 mass%, the storage stability and heat resistance may be poor. However, in either case, the object of the present invention can be achieved.

[0041] The total content of the styrene-(meth)acrylic resin (B) and the dispersing resin (C) in the solids of the liquid composition (excluding colorants such as pigments) is 10 to 30% by mass, preferably 10 to 28% by mass, and even more preferably 11 to 25% by mass from the viewpoint of further improving blocking resistance, abrasion resistance, heat resistance, and alkali release property. By keeping the total content of the styrene-(meth)acrylic resin (B) and the dispersing resin (C) within the above range, the blocking resistance, heat resistance, and alkali release property of the printed layer can be improved. If the total content of the styrene-(meth)acrylic resin (B) and the dispersing resin (C) is less than 10% by mass, the alkali release property of the printed layer decreases. On the other hand, if the total content of the styrene-(meth)acrylic resin (B) and the dispersing resin (C) exceeds 30% by mass, the blocking resistance of the printed layer formed on the substrate composed of A-PET and LLDPE decreases, and the heat resistance of the printed layer formed on the substrate composed of A-PET and HDPE decreases.

[0042] The content of the dispersion resin (C) relative to 1 part by mass of the styrene-(meth)acrylic resin (B) in the solids content of the liquid composition (excluding colorants such as pigments) is 0.1 to 1.5 parts by mass, preferably 0.15 to 1.2 parts by mass, and even more preferably 0.3 to 0.8 parts by mass from the viewpoint of further improving blocking resistance, heat resistance, and alkali release properties. By keeping the content of the dispersion resin (C) relative to 1 part by mass of the styrene-(meth)acrylic resin (B) within the above range, the alkali release properties of the printed layer can be improved. If the content of the dispersion resin (C) relative to 1 part by mass of the styrene-(meth)acrylic resin (B) is less than 0.1 part by mass, the alkali release properties of the resulting printed layer are reduced. On the other hand, if the content of the dispersion resin (C) relative to 1 part by mass of the styrene-(meth)acrylic resin (B) is more than 1.5 parts by mass, the alkali release properties of the printed layer formed on a substrate made of A-PET and HDPE are reduced.

[0043] The total content of the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B), and the dispersing resin (C) in the solid content of the liquid composition (excluding colorants such as pigments) is 65 to 100% by mass, and more preferably 70 to 100% by mass from the viewpoint of further improving adhesion, blocking resistance, and abrasion resistance. By ensuring that the total content of the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B), and the dispersing resin (C) in the solid content of the liquid composition (excluding colorants such as pigments) is within the above range, the blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali release property of the printed layer can be improved. On the other hand, if the total content of the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B), and the dispersing resin (C) in the solid content of the liquid composition (excluding colorants such as pigments) is less than 65% by mass, the blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali release property will be inferior.

[0044] (silica) The resin composition can further contain silica. The use of silica can further improve the blocking resistance of the printed layer. Silica may be either natural or synthetic. Synthetic silica may be synthesized by either a dry method or a wet method. Known dry methods include the combustion method and the arc method, and known wet methods include the precipitation method and the gel method, and silica synthesized by either method may be used. Furthermore, silica may be either crystalline or amorphous, and may be either hydrophobic or hydrophilic. These silicas may be used alone or in combination of two or more types.

[0045] The average particle size of the silica is preferably 1.0 to 8.0 μm, and more preferably 2.0 to 6.5 μm. In this specification, the term "average particle size" refers to the cumulative 50% particle size (median diameter; D) in the volume-based particle size distribution. 50 The solid content of silica is preferably 0.3 to 5.0 mass %, and more preferably 0.5 to 3.0 mass %, based on the total solid content of the liquid composition (excluding colorants such as pigments).

[0046] (cellulose resin) The resin composition can further contain a cellulose resin. The use of a cellulose resin can improve the blocking resistance, abrasion resistance, and heat resistance of the printed layer. Examples of cellulose-based resins include cellulose and cellulose derivatives in which at least a portion of the hydroxyl groups of cellulose have been substituted with other groups, with cellulose derivatives being preferred. Examples of cellulose derivatives include nitrocellulose (nitro group-substituted cellulose); lower acyl group-substituted cellulose such as cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate; lower alkyl group-substituted cellulose such as methylcellulose and ethylcellulose; aralkyl group-substituted cellulose such as benzylcellulose; and hydroxyalkyl group-containing cellulose derivatives such as hydroxyethylcellulose, hydroxypropylcellulose, and hydroxymethylpropylcellulose, with nitrocellulose being preferred. These cellulose-based resins may be used alone or in combination. The weight-average molecular weight of the cellulose resin is preferably 5,000 to 200,000, more preferably 10,000 to 100,000.

[0047] The solid content of the cellulose resin is preferably 5 to 40 mass %, more preferably 10 to 30 mass %, based on the total solid content of the liquid composition (excluding colorants such as pigments). By keeping the cellulose resin content within the above range, it is possible to improve blocking resistance and abrasion resistance while maintaining adhesion to the substrate.

[0048] (Other resins) The resin composition may further contain resins (other resins) other than the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B), and the dispersion resin (C). Examples of other resins include those that can be contained in liquid compositions such as ordinary inks, provided that they do not affect the effects of this embodiment. More specifically, examples of such other resins include soluble nitrocellulose, urethane resins, polyamide resins, and chlorinated polypropylene resins.

[0049] (solvent) The resin composition of this embodiment is used as a liquid composition containing a specific ratio of alcohol-based solvents and ester-based solvents as the main solvents. In one preferred embodiment, the resin composition contains water or an organic solvent other than the alcohol-based solvent and the ester-based solvent, provided that the effects of this embodiment are not affected. The content of the solvent relative to the total mass of the liquid composition is preferably 20 to 80% by mass, more preferably 25 to 75% by mass, and particularly preferably 30 to 70% by mass.

[0050] The liquid composition contains a solvent including an alcohol-based solvent and an ester-based solvent. The total content of the alcohol-based solvent and the ester-based solvent in the solvent is 90 to 100% by mass, and from the viewpoint of further improving storage stability, it is preferably 95 to 100% by mass. By using a solvent including an alcohol-based solvent and an ester-based solvent and by keeping the content of these solvents in the solvent within the above ranges, it is possible to form a printed layer that can suppress whitening of substrates made of A-PET, HDPE, and LLDPE. On the other hand, if the total content of the alcohol-based solvent and the ester-based solvent is less than 90% by mass, the storage stability of the ink will be poor, or the A-PET substrate will whiten.

[0051] Furthermore, the mass ratio of the alcohol-based solvent to the ester-based solvent in the solvent contained in the liquid composition is 2.5:7.5 to 7:3, and more preferably 3:7 to 6.5:3.5 from the viewpoints of suppressing whitening of the substrate and providing better storage stability. By keeping the mass ratio of the alcohol-based solvent to the ester-based solvent in the solvent within the above range, it is possible to form a printed layer that has excellent storage stability and can suppress whitening of substrates made of A-PET, HDPE, and LLDPE.

[0052] Examples of alcohol-based solvents include isopropyl alcohol, methanol, ethanol, n-propanol, and n-butanol. These alcohol-based solvents can be used alone or in combination of two or more. Examples of ester-based solvents include ethyl acetate, propyl acetate, and isobutyl acetate. These ester-based solvents can be used alone or in combination of two or more. When an alcohol-based solvent is used alone, the storage stability of the ink is poor. On the other hand, when an ester-based solvent is used alone, the substrate whitens, and the desired printed matter cannot be obtained.

[0053] When an alcohol-based solvent or an ester-based solvent is not used as the main solvent, specifically when a hydrocarbon-based, ketone-based, or glycol ether-based solvent is used as the main solvent, the substrate will whiten and the storage stability of the liquid composition will be poor.

[0054] (Method for preparing resin composition) The resin composition of this embodiment can be prepared by mixing the above-mentioned components according to a conventional method. The (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) components constituting the resin composition may each be liquid or solid. That is, the resin composition may be a liquid composition obtained by mixing a liquid component with a solid component, a liquid composition obtained by mixing all liquid components, or a solid composition obtained by mixing all solid components. Furthermore, various additives may be further contained as necessary.

[0055] By using the resin composition of this embodiment, it is possible to easily prepare liquid compositions such as inks, mediums, primers, and overcoat varnishes for forming the removable printing layers described below. That is, by mixing the resin composition with conventionally known components used in inks and the like in a conventional manner, it is possible to prepare liquid compositions that can form printed layers on substrates made of A-PET, HDPE, and LLDPE, which are easily removable under mild alkaline conditions and have excellent storage stability, blocking resistance, adhesion, abrasion resistance, heat resistance, and alkaline release properties, and which can suppress whitening of the substrate.

[0056] <Liquid composition> The liquid composition of the present invention is a liquid composition for forming a removable printing layer on a substrate formed of at least one resin selected from the group consisting of amorphous polyethylene terephthalate (A-PET), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE). A first embodiment of the liquid composition of the present invention contains a solvent containing an alcohol-based solvent and an ester-based solvent, a printing composition for forming a non-detachable printing layer, and the aforementioned resin composition. The total content of the alcohol-based solvent and the ester-based solvent in the solvent is 90 to 100 mass%, and the mass ratio of the alcohol-based solvent to the ester-based solvent is 2.5:7.5 to 7:3.

[0057] A second embodiment of the liquid composition of the present invention contains a (meth)acrylic resin (A) having an acid value of less than 25 mgKOH / g, a styrene-(meth)acrylic resin (B) having an acid value of 25 to 90 mgKOH / g, a dispersing resin (C) having an acid value of 150 to 400 mgKOH / g, and a solvent including an alcohol-based solvent and an ester-based solvent. The total content of the styrene-(meth)acrylic resin (B) and the dispersing resin (C) in the solid content of the liquid composition (excluding colorants such as pigments) is 10 to 30 mass %, the content of the dispersing resin (C) is 0.1 to 1.5 mass parts per part by mass of the styrene-(meth)acrylic resin (B), and the total content of the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B), and the dispersing resin (C) in the solid content of the liquid composition (excluding colorants such as pigments) is 65 to 100 mass %. The total content of the alcohol-based solvent and the ester-based solvent in the solvent is 90 to 100 mass %, and the mass ratio of the alcohol-based solvent to the ester-based solvent is 2.5:7.5 to 7:3. Hereinafter, the "liquid composition of the first embodiment" and the "liquid composition of the second embodiment" will also be collectively referred to as the "liquid composition of the present embodiment."

[0058] The liquid composition of the first embodiment contains the resin composition described above, and therefore contains the (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) in predetermined contents and mass ratios. The liquid composition of the second embodiment contains the (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) in predetermined contents and mass ratios. Therefore, by using the liquid composition of this embodiment, a printed layer that is storage stable, easily detached under mild alkaline conditions, and has excellent blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali detachment properties can be formed on a substrate made of A-PET, HDPE, or LLDPE while suppressing whitening of the substrate. The components of the (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) are the same as the components of the (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C) used in the resin composition described above.

[0059] The content of the (meth)acrylic resin (A) in the solid content of the liquid composition (excluding colorants such as pigments) may be appropriately set depending on the intended use, etc. For example, the content of the (meth)acrylic resin (A) is preferably 40 to 75 mass %, more preferably 50 to 70 mass %, based on the solid content of the liquid composition, and particularly preferably 59 to 65 mass % from the viewpoint of achieving better blocking resistance, adhesion, and alkali release properties of the printed layer. By setting the content of the (meth)acrylic resin (A) within the above range, the blocking resistance, adhesion, and alkali release properties of the printed layer can be improved. If the content of the (meth)acrylic resin (A) is less than 40 mass %, the adhesion of the ink layer may be poor, and if it is more than 75 mass %, the alkali release properties and blocking resistance of the ink layer may be poor. However, in either case, the object of the present invention can be achieved.

[0060] The solid content of the (meth)acrylic resin (A) in the total mass of the liquid composition (excluding colorants such as pigments) may be appropriately set depending on the intended use, etc. For example, the solid content of the (meth)acrylic resin (A) is preferably 1 to 50 mass%, more preferably 3 to 35 mass%, based on the total mass of the liquid composition, and particularly preferably 5 to 20 mass% from the viewpoint of achieving better ink storage stability, blocking resistance, adhesion, and alkali release properties of the printed layer. By setting the solid content of the (meth)acrylic resin (A) within the above range, storage stability, and the blocking resistance, adhesion, and alkali release properties of the printed layer can be improved. If the solid content of the (meth)acrylic resin (A) is less than 1 mass%, the ink layer may have poor adhesion, and if it exceeds 50 mass%, the ink layer may have poor alkali release properties and blocking resistance. However, in either case, the object of the present invention can be achieved.

[0061] The content of the styrene-(meth)acrylic resin (B) in the solid content of the liquid composition (excluding colorants such as pigments) may be appropriately set depending on the intended use, etc. For example, the content of the styrene-(meth)acrylic resin (B) is preferably 4 to 28 mass %, more preferably 5 to 17 mass %, based on the solid content of the liquid composition, and particularly preferably 6 to 14 mass % from the viewpoint of achieving better blocking resistance and alkali release properties of the printed layer. By setting the content of the styrene-(meth)acrylic resin (B) within the above range, the blocking resistance and alkali release properties of the printed layer can be improved. If the content of the styrene-(meth)acrylic resin (B) is less than 4 mass %, alkali release properties may be poor, and if it is more than 28 mass %, blocking resistance may be poor. However, in either case, the object of the present invention can be achieved.

[0062] The solid content of the styrene-(meth)acrylic resin (B) in the total mass of the liquid composition (excluding colorants such as pigments) may be appropriately set depending on the intended use, etc. For example, the solid content of the styrene-(meth)acrylic resin (B) is preferably 0.1 to 10.0 mass%, more preferably 1.0 to 8.0 mass%, based on the total mass of the liquid composition, and particularly preferably 1.0 to 6.0 mass%, from the viewpoint of achieving better blocking resistance, alkali release properties, and water resistance of the printed layer. By setting the content of the styrene-(meth)acrylic resin (B) within the above range, storage stability and the blocking resistance and alkali release properties of the printed layer can be improved. If the solid content of the styrene-(meth)acrylic resin (B) is less than 0.1 mass%, alkali release properties may be poor, and if it exceeds 10.0 mass%, blocking resistance may be poor. However, in either case, the object of the present invention can be achieved.

[0063] The content of the dispersing resin (C) in the solid content of the liquid composition (excluding colorants such as pigments) may be appropriately set depending on the intended use, etc. For example, the content of the dispersing resin (C) is preferably 0.9 to 18 mass%, more preferably 2 to 10 mass%, and particularly preferably 3 to 5.5 mass%, based on the solid content of the liquid composition, from the viewpoint of further improving alkali release properties and heat resistance. By setting the content of the dispersing resin (C) within the above range, the storage stability, alkali release properties, and heat resistance of the printed layer can be improved. If the content of the dispersing resin (C) is less than 0.9 mass%, the releasability of the printed layer may be poor, and if it exceeds 18 mass%, the storage stability and heat resistance may be poor. However, in either case, the object of the present invention can be achieved.

[0064] The solid content of the dispersion resin (C) relative to the total mass of the liquid composition (excluding colorants such as pigments) may be appropriately determined depending on the intended use. For example, the solid content of the dispersion resin (C) is preferably 0.05 to 5.0 mass%, more preferably 0.1 to 4.0 mass%, based on the total mass of the liquid composition. From the viewpoint of achieving better storage stability, alkali releasability, and heat resistance of the printed layer, 0.15 to 3.0 mass% is particularly preferred. By setting the solid content of the dispersion resin (C) within the above range, the storage stability, alkali releasability, and heat resistance of the printed layer can be improved. If the solid content of the dispersion resin (C) is less than 0.05 mass%, the releasability of the printed layer may be poor, and if it exceeds 5 mass%, the storage stability and heat resistance may be poor. However, in either case, the object of the present invention can be achieved.

[0065] The total content of the styrene-(meth)acrylic resin (B) and the dispersing resin (C) in the solids content of the liquid composition (excluding colorants such as pigments) is 10 to 30% by mass, preferably 11 to 25% by mass, and more preferably 11 to 20% by mass. By keeping the total content of the styrene-(meth)acrylic resin (B) and the dispersing resin (C) within the above range, the blocking resistance, heat resistance, and alkali release properties of the printed layer can be improved. If the total content of the styrene-(meth)acrylic resin (B) and the dispersing resin (C) is less than 10% by mass, the alkali release properties of the printed layer will be reduced. On the other hand, if the total content of the styrene-(meth)acrylic resin (B) and the dispersing resin (C) is more than 30% by mass, the blocking resistance of the printed layer formed on a substrate made of A-PET and LLDPE will be reduced, and the heat resistance of the printed layer formed on a substrate made of A-PET and HDPE will be reduced.

[0066] The content of the dispersion resin (C) relative to 1 part by mass of the styrene-(meth)acrylic resin (B) in the solids content of the liquid composition (excluding colorants such as pigments) is 0.1 to 1.5 parts by mass, preferably 0.15 to 1.2 parts by mass, and even more preferably 0.3 to 0.8 parts by mass from the viewpoint of further improving blocking resistance, heat resistance, and alkali release properties. By keeping the content of the dispersion resin (C) relative to 1 part by mass of the styrene-(meth)acrylic resin (B) within the above range, the alkali release properties of the printed layer can be improved. If the content of the dispersion resin (C) relative to 1 part by mass of the styrene-(meth)acrylic resin (B) is less than 0.1 part by mass, the alkali release properties of the resulting printed layer are reduced. On the other hand, if the content of the dispersion resin (C) relative to 1 part by mass of the styrene-(meth)acrylic resin (B) is more than 1.5 parts by mass, the alkali release properties of the printed layer formed on a substrate made of A-PET and HDPE are reduced.

[0067] The total content of the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B), and the dispersing resin (C) in the solid content of the liquid composition (excluding colorants such as pigments) is 65 to 100% by mass, and more preferably 70 to 100% by mass from the viewpoint of further improving adhesion, blocking resistance, and abrasion resistance. By ensuring that the total content of the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B), and the dispersing resin (C) in the solid content of the liquid composition (excluding colorants such as pigments) is within the above range, the blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali release property of the printed layer can be improved. On the other hand, if the total content of the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B), and the dispersing resin (C) in the solid content of the liquid composition (excluding colorants such as pigments) is less than 65% by mass, the blocking resistance, adhesion, abrasion resistance, heat resistance, and alkali release property will be inferior.

[0068] The liquid composition of the first embodiment can be prepared, for example, by adding and mixing the aforementioned resin composition to a printing composition such as an ink, medium, primer, or overcoat varnish for forming a non-detachable printing layer, which contains each of the conventionally known components.

[0069] The liquid composition of the second embodiment can be prepared by adding and mixing various components that are incorporated into general printing compositions, such as inks, mediums, primers, and overcoat varnishes, to the above-mentioned resin composition.

[0070] (optional ingredient) The liquid composition of this embodiment may further contain silica, pigments, cellulose resins, other resins, and various additives as components other than the (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C). The silica and cellulose resins are the same as those usable in the resin composition described above.

[0071] The solid content of silica in the liquid composition is preferably 0.1 to 1.5 mass %, more preferably 0.2 to 1.0 mass %, based on the solid content of the liquid composition (excluding colorants such as pigments).

[0072] The solid content of the cellulose resin is preferably 5 to 40 mass %, more preferably 10 to 30 mass %, based on the total solid content of the liquid composition (excluding colorants such as pigments). By setting the content of the cellulose resin within the above range, pigment dispersibility can be further improved.

[0073] [Pigment] The pigment may be a general pigment used in inks such as gravure printing inks, etc. Examples of the pigment include inorganic pigments such as ultramarine, Prussian blue, cobalt blue, red iron oxide, iron black, yellow iron oxide, titanium dioxide, and carbon black, and organic pigments such as monoazo pigments, disazo pigments, condensed azo pigments, phthalocyanine pigments, anthraquinone pigments, quinacridone pigments, isoindolinone pigments, thioindigo pigments, and pyrrolopyrrole pigments.

[0074] The content of the pigment in the liquid composition may be appropriately set depending on the color tone, density, etc. of the printing layer (printed matter) to be formed. Specifically, the solid content of the pigment is usually 80% by mass or less, and preferably 70% by mass or less, based on the solid content of the liquid composition.

[0075] [Other resins] The other resin is a resin other than the above-mentioned (meth)acrylic resin (A), styrene-(meth)acrylic resin (B), and dispersion resin (C). Examples of the other resin include soluble nitrocellulose, urethane resin, polyamide resin, and chlorinated polypropylene resin, provided that they do not affect the liquid composition of the present embodiment.

[0076] [Additives] The liquid composition may contain additives such as extender pigments, waxes, synthetic resin powders, antifoaming agents, dispersants, and plasticizers in order to maintain the properties of the liquid composition such as viscosity and fluidity, to plasticize the printing layer (printing surface), and to impart slip properties to the printing layer (printing surface).

[0077] Examples of extender pigments include alumina white, talc, precipitated barium sulfate, and calcium carbonate. Examples of waxes include polyethylene wax, polypropylene wax, paraffin wax, carnauba wax, and ozokerite. Examples of synthetic resin powders include acrylic resin powder, polyurethane resin powder, polyimide resin powder, melamine resin powder, benzoguanamine resin powder, and silicone resin powder. Examples of plasticizers include dibutyl phthalate, dioctyl phthalate, dioctyl adipate, and triethyl citrate.

[0078] The inclusion of wax in the liquid composition is preferable because it can improve the abrasion resistance of the resulting printed layer. The solid content of the wax in the liquid composition is preferably 0.1 to 5.0 mass %, and more preferably 0.5 to 3.0 mass %, based on the total solid content of the liquid composition.

[0079] (Method for preparing liquid composition) The liquid composition of this embodiment can be prepared by mixing the above-mentioned components in a conventional manner.

[0080] For example, the liquid composition of the second embodiment can be prepared by adding and mixing various components that are incorporated into general printing compositions such as ink, medium, primer, and overcoat varnish to the above-mentioned resin composition.

[0081] Furthermore, the liquid composition of the first embodiment can be prepared by adding and mixing the above-described styrene-(meth)acrylic resin (B) and dispersion resin (C) to a predetermined content and mass ratio in a general printing composition such as an ink, medium, primer, or overcoat varnish for forming a non-detaching printing layer containing the (meth)acrylic resin (A) as a binder resin. That is, by appropriately adding and mixing the above-described styrene-(meth)acrylic resin (B) and dispersion resin (C) to a liquid composition such as an ink for forming a non-detaching printing layer, the liquid composition for forming a non-detaching printing layer can be converted into a liquid composition capable of forming a detaching printing layer.

[0082] The liquid composition of this embodiment can be used in mediums, primers, overcoat varnishes, and inks containing colorants. The liquid composition of this embodiment can be suitably used not only as an ink containing a colorant (colorant) such as a pigment, but also as mediums, primers, and overcoat varnishes that are substantially free of pigment. Printed materials can be produced by combining an ink containing a pigment with at least one of a medium, primer, and overcoat varnish that does not contain a pigment. In particular, from the standpoint of compatibility, it is preferable to combine an ink having the same composition of components other than the pigment with at least one of a medium, primer, and overcoat varnish.

[0083] By using a medium, primer, overcoat varnish, or ink containing a colorant made using the liquid composition of this embodiment, a printed layer with excellent adhesion can be formed on a substrate made of at least one resin selected from the group consisting of A-PET, HDPE, and LLDPE. Specifically, when cellophane tape is applied to a portion of the surface of a printed layer formed by applying the liquid composition to a substrate made of the above resin and then quickly peeled off, the ratio of the area of ​​the peeled printed layer to the adhesive area of ​​the cellophane tape is less than 20%, preferably less than 15%.

[0084] <Removable Printed Layer and Laminate> One embodiment of the removable printed layer of the present invention is a printed layer formed from a medium, primer, overcoat varnish, or ink containing a colorant, using the liquid composition described above, disposed on a substrate formed from at least one resin selected from the group consisting of amorphous polyethylene terephthalate (A-PET), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE). Another embodiment of the laminate of the present invention comprises a substrate formed from at least one resin selected from the group consisting of amorphous polyethylene terephthalate (A-PET), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE), and a printed layer formed from the liquid composition described above disposed on the substrate. That is, by using the liquid composition described above, a removable printed layer that can be easily removed by treatment under mild alkaline conditions, and a laminate comprising this removable printed layer, can be obtained. Furthermore, the printed layer formed with the medium, primer, overcoat varnish, or ink containing a colorant not only has excellent alkali release properties, but also has excellent properties as a printed matter, such as blocking resistance, adhesion, abrasion resistance, and heat resistance, and the substrate is less likely to whiten. Therefore, the laminate of this embodiment has excellent recyclability, ease of handling, design, etc.

[0085] A specific example of the laminate configuration is a laminate (laminate-1) comprising a first substrate and a removable printed layer formed with a medium, primer, overcoat varnish, or ink containing a colorant, made using a liquid composition. Laminate-1 may further comprise layers other than the first substrate and the removable printed layer. Examples of other layers include a design layer formed using printing ink, and a vapor-deposited layer formed by vapor-depositing a metal or metal oxide, such as aluminum or silica.

[0086] After applying the liquid composition to the first substrate, the volatile components are removed to form a removable printed layer on the first substrate. The liquid composition can be easily and stably applied to the first substrate using a gravure coater, knife coater, reverse coater, bar coater, spray coater, slit coater, or the like. The thickness of the printed layer is preferably 0.5 to 10 μm, and more preferably 1 to 5 μm.

[0087] Another specific example of a laminate configuration is a laminate (laminate-2) that further comprises a second substrate in addition to laminate-1. That is, laminate-2 is a laminate having a so-called laminate structure that comprises a first substrate, a second substrate, and a removable printed layer. Laminate-2 may further comprise layers other than the first substrate, the second substrate, and the removable printed layer. Examples of other layers include a pattern layer formed using printing ink, and a vapor-deposited layer formed by vapor-depositing a metal or metal oxide such as aluminum or silica. Alternatively, laminate-2 may be a laminate film in which a first substrate, a removable printed layer, an adhesive layer, and a second substrate are laminated in this order.

[0088] The laminate film can be easily produced, for example, by the following method. First, an adhesive is applied to the surface of the removable printing layer of the laminate-1 to form an adhesive layer. Next, a second substrate is attached to the surface of the formed adhesive layer to produce the laminate film.

[0089] The substrates such as the first substrate and the second substrate may be, for example, plastic films formed from at least one resin selected from the group consisting of amorphous polyethylene terephthalate (A-PET), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE). The surface of the substrate may be corona discharge treated. The substrate may be made of recycled materials that have been recovered after being used once as a printed matter. The substrate may be stretched or unstretched. The substrate may also be one on which metals or metal oxides such as silica, alumina, and aluminum are vapor-deposited, or one on which the vapor-deposited surface is coated with a paint such as polyvinyl alcohol.

[0090] The substrate may be one produced by a conventional method or a commercially available product, such as "NOA CRYSTAL-V" and "NOA CRYSTAL-R" manufactured by RP Toho Plastics Co., Ltd., or "TC400" and "HD" manufactured by Tamapoly Corporation.

[0091] The shape of the substrate is not particularly limited, and a substrate of a shape according to the purpose can be used. Specific examples of the shape of the substrate include a film and a sheet. Further specific examples of the shape of the substrate include various containers such as cups, plates, bowls, and bottles, and lids such as caps. By applying a liquid composition such as ink to the surface of the substrate using a general printing method such as gravure printing, a removable printed layer having a desired design, information, etc. is formed, and the desired laminate can be obtained.

[0092] The laminate of this embodiment, which includes a removable printed layer formed with the above-mentioned ink, medium, primer, overcoat varnish, or the like, is useful, for example, as a label or packaging. More specifically, the laminate of this embodiment is suitable for containers for storing food, soft drinks, cosmetics, seasonings, medicines, sanitary products, etc.; labels to be attached to these containers; resin bags (packaging materials) for storing foods such as bread, rice balls, and side dishes; lids for sealing containers and bottles; etc. Among these, since many food and beverage containers are recycled, the laminate is particularly suitable for food and beverage containers, labels to be attached to food and beverage containers, lids for food and beverage containers, etc.

[0093] <How to remove the printed layer> One embodiment of the method for removing a printed layer of the present invention includes a step of contacting the printed layer of the laminate with an alkaline aqueous solution to remove and remove the printed layer from the substrate. The printed layer provided on the substrate constituting the laminate is a layer formed from the liquid composition, and therefore can be easily removed under mild alkaline conditions.

[0094] To remove the printed layer disposed on the substrate, the laminate can be immersed in an alkaline aqueous solution, for example, to bring the printed layer into contact with the alkaline aqueous solution. The alkaline aqueous solution can be prepared by dissolving various alkalis in water. Examples of alkalis include ammonia, sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium bicarbonate, potassium bicarbonate, sodium carbonate, and potassium carbonate. From the viewpoint of versatility, it is preferable to use an aqueous sodium hydroxide solution as the alkaline aqueous solution. By immersing the laminate in a 1 to 7.5 mass % aqueous sodium hydroxide solution for 5 to 60 minutes, the printed layer can be easily removed from the substrate, resulting in a clean, recyclable substrate. The temperature of the alkaline aqueous solution, such as the sodium hydroxide aqueous solution, in which the laminate is immersed can be set to room temperature (25°C) to 90°C.

[0095] For example, when treating the aforementioned laminate-2, the laminate-2 is immersed in a 1.5% by mass aqueous solution of sodium hydroxide and stirred for about 30 minutes at 80° C. This allows the printed layer to be detached from the first substrate and the second substrate.

[0096] The removal method of the present embodiment preferably further includes a step of recovering the substrate from which the printed layer has been removed. For example, if 80% or more of the printed layer has been peeled off from the substrate, the substrate can be reused as a recycled film simply by cleaning the surface by washing with water, drying, or the like. [Example]

[0097] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are by mass unless otherwise specified.

[0098] <Preparation of various raw materials> (Resin (A)) Resins (A) of the type shown in Table 1 were prepared.

[0099] TIFF0007777710000001.tif64170

[0100] (Resin (B)) The types of resins (B) shown in Table 2 were prepared.

[0101] TIFF0007777710000002.tif51170

[0102] (Dispersion resin (C)) Dispersion resin (C) (resin (C)) of the type shown in Table 3 was prepared.

[0103] TIFF0007777710000003.tif48170

[0104] (silica) As silica, S-1 and S-2 shown below were prepared. S-1: Product name "ACEMAT OK412", manufactured by EVONIK, average particle size 6.3 μm S-2: Product name "Nipsil E220A", manufactured by Tosoh Silica Corporation, average particle size 4.2 μm

[0105] (Other ingredients) The following ingredients were prepared: Pigment: Seika First Carmine 3870, manufactured by Dainichi Seika Color & Chemicals Co., Ltd. Antifoaming agent: BYK-1752, manufactured by BYK Dispersant: Solsperse 20000, manufactured by Lubrizol, acid value 0 mg KOH / g Plasticizer: Citroflex A-4, manufactured by Morimura Shoji Co., Ltd. Solvents: Isopropanol (IPA), methanol, ethyl acetate, propyl acetate, hydrocarbon solvents (toluene), ketone solvents (methyl ethyl ketone), glycol ether solvents (diethylene glycol methyl ether), water

[0106] <Preparation of Liquid Composition (Ink)> The components were mixed to obtain mixtures with the compositions (units: %) shown in the upper rows of Tables 4-1 to 4-5. The resulting mixtures were kneaded using a paint shaker to prepare liquid compositions (inks). In Tables 4-1 to 4-5, "Alc" stands for alcohol-based solvents, and "Est" stands for ester-based solvents.

[0107] TIFF0007777710000004.tif255164

[0108] TIFF0007777710000005.tif255164

[0109] TIFF0007777710000006.tif255160

[0110] TIFF0007777710000007.tif237170

[0111] TIFF0007777710000008.tif243170

[0112] <Production of laminate> The following three types of substrate films were prepared. A-PET sheet with one side corona discharge treated (product name "NOA CRYSTAL-V", manufactured by RP Toho Plastics, thickness 250 μm) - HDPE film with corona discharge treatment on one side (product name "Kararyan Y", manufactured by Denka Co., Ltd., thickness 18 μm) - LLDPE film with one side corona discharge treated (product name "HC", manufactured by RM Tocello Co., Ltd., thickness 25 μm)

[0113] The prepared liquid composition was diluted with a mixed solvent (methylcyclohexane / propyl acetate / isopropyl alcohol). The diluted release ink liquid composition was applied to the treated surface of each substrate film by gravure printing using a 70-line heliostat. This resulted in a laminate in which a printed layer (100 mm x 150 mm solid layer, 1 μm thick) was formed on the substrate film.

[0114] <Rating (1)> (Storage stability) The prepared ink was allowed to stand at 40°C for 5 days from the next day onwards. The viscosity of the ink after standing was measured using a Zahn cup, and the storage stability (fluidity) of the liquid composition was evaluated according to the following evaluation criteria. The results are shown in Tables 5-1 and 5-2. ○: Viscosity increased slightly. △: Viscosity increased for 10 seconds or more. ×: Gelling occurred or the raw materials precipitated.

[0115] (blocking resistance) The surface of the printed layer was placed on the non-printed side of the same base film to prepare a test piece, and a pressure of 4 kg / cm 2 The test pieces were stored in a thermostatic chamber at 40°C for 24 hours with a load of 1000 kJ / cm2 applied. After storage, the test pieces were peeled off and the blocking resistance of the printed layer was evaluated according to the following evaluation criteria. The results are shown in Tables 5-1 and 5-2. 5: The area ratio of the printed layer transferred to the non-printed surface was 0% or more and less than 10%. 4: The area ratio of the printed layer transferred to the non-printed surface was 10% or more and less than 20%. 3: The area ratio of the printed layer transferred to the non-printed surface was 20% or more but less than 50%. 2: The area ratio of the printed layer transferred to the non-printed surface was 50% or more but less than 80%. 1: The area ratio of the printed layer transferred to the non-printed surface was 80% or more and 100% or less.

[0116] (adhesion) After applying cellophane tape (manufactured by Nichiban Co., Ltd.) to a portion of the surface of the ink layer, the cellophane tape was quickly peeled off, and the state of the ink layer remaining on the base film (plastic film) was visually inspected, and the adhesion of the ink layer to the base film (plastic film) was evaluated according to the following criteria. The results are shown in Tables 5-1 and 5-2. 5: The ratio of the area of ​​the peeled ink layer to the adhesive area of ​​the cellophane tape is less than 10%. 4: The ratio of the area of ​​the peeled ink layer to the adhesive area of ​​the cellophane tape is 10% or more but less than 20%. 3: The ratio of the area of ​​the peeled ink layer to the adhesive area of ​​the cellophane tape is 20% or more but less than 50%. 2: The ratio of the area of ​​the peeled ink layer to the adhesive area of ​​the cellophane tape is 50% or more but less than 80%. 1: The ratio of the area of ​​the peeled ink layer to the adhesive area of ​​the cellophane tape is 80% or more.

[0117] (Abrasion resistance) A friction test was conducted using a Gakushin-type abrasion fastness tester (product name "AB-301", manufactured by Tester Sangyo Co., Ltd.) in which the surface of the printed layer was rubbed back and forth 200 times with a No. 3 gold duster under a load of 200 gf. The appearance of the printed layer after the abrasion test was visually inspected, and the abrasion resistance of the printed layer was evaluated according to the following evaluation criteria. The results are shown in Tables 5-1 and 5-2. 5: The area ratio of the printed layer that migrated to the No. 3 gold sheet was 0% or more and less than 10%. 4: The area ratio of the printed layer that migrated to the No. 3 gold sheet was 10% or more but less than 20%. 3: The area ratio of the printed layer that migrated to the No. 3 gold sheet was 20% or more but less than 50%. 2: The area ratio of the printed layer that migrated to the No. 3 gold sheet was 50% or more but less than 80%. 1: The area ratio of the printed layer that migrated to the No. 3 gold sheet was 80% or more and 100% or less.

[0118] (Heat resistance) A test piece was prepared by overlapping the surface of the printed layer with soft aluminum foil. Using a heat seal tester (product name "TP-701-C Heat Seal Tester", manufactured by Tester Sangyo Co., Ltd.), a test piece was applied from the aluminum foil to the test piece at 100 to 120°C and 2 kg / cm. 2 After heating, the test piece was peeled off and the heat resistance of the printed layer was evaluated according to the following evaluation criteria. The results are shown in Tables 5-1 and 5-2. 5: Even when heated at 150°C, the printing layer (liquid composition for releasable ink) was not removed from the aluminum foil. 4: When heated to 140°C, the printing layer (liquid composition for releasable ink) was not removed from the aluminum foil, but when heated to 150°C, the ink was removed. 3: When heated up to 130°C, the printing layer (liquid composition for releasable ink) was not removed from the aluminum foil, but when heated to 140°C, the ink was removed. 2: When heated to 120°C, the printing layer (liquid composition for releasable ink) was not removed from the aluminum foil, but when heated to 130°C, the ink was removed. 1: A printing layer (liquid composition for release ink) was applied to the aluminum foil by heating at less than 120°C.

[0119] (alkali elimination) The laminate was immersed in a 4.5% aqueous sodium hydroxide solution at 80°C and stirred for 30 minutes. After removing the laminate from the aqueous sodium hydroxide solution and rinsing it with water, it was visually observed and the releasability of the printed layer was evaluated according to the following evaluation criteria. The results are shown in Tables 5-1 and 5-2. 5: The printed layer was completely detached. 4: Part of the printed layer remained on the base film. 3: About half of the printed layer remained on the base film. 2: Most of the printed layer remained on the base film. 1: The printed layer was not detached at all.

[0120] TIFF0007777710000009.tif110170

[0121] TIFF0007777710000010.tif129170

[0122] Additionally, laminate-2 was produced and evaluated in the same manner as in the above-mentioned "alkali release property." As a result, it was confirmed that all laminate-2s exhibited excellent alkali release property equivalent to that of the above-mentioned examples.

[0123] <Evaluation (2)> (Whitening resistance) The liquid compositions prepared in Examples 1, 22 to 29, and Comparative Examples 14 to 21 were applied to the three types of substrate films used in the "Laminate Production" section above for printing, and then the liquid compositions were wiped off with IPA. The surfaces of the substrate films were visually inspected, and the whitening resistance was evaluated according to the following evaluation criteria. The results are shown in Table 6. ○: No whitening was observed. △: Slightly bleached. ×: Severe bleaching.

[0124] (Storage stability) The storage stability (fluidity) of the liquid compositions prepared in Examples 1, 22 to 29 and Comparative Examples 14 to 21 was evaluated in the same manner as in the above-mentioned "storage stability." The results are shown in Table 6.

[0125] TIFF0007777710000011.tif46170

[0126] <Rating (3)> (adhesion and alkali release) Liquid compositions (inks) were prepared in the same manner as in Example 1, except that solvents (IPA:ethyl acetate) were used in the mass ratio shown in Table 7. In addition, the following six types of substrate films were prepared. Shrink PS: Shrink polystyrene OPS: Biaxially oriented polystyrene CPS: Non-oriented polystyrene OPP: Biaxially oriented polypropylene PET: Polyethylene terephthalate ONY: Biaxially oriented nylon

[0127] The prepared liquid composition was diluted with a mixed solvent (methylcyclohexane / propyl acetate / isopropyl alcohol). The diluted liquid composition for release ink was applied to the treated surface of each prepared substrate film by gravure printing using a 70-line heliostat. This resulted in a laminate with a printed layer (100 mm x 150 mm solid layer, 1 μm thick) formed on the substrate film. The obtained laminate was then evaluated in the same manner as described above for "adhesion" and "alkali release property." The results are shown in Table 7.

[0128] TIFF0007777710000012.tif123170

[0129] In Comparative Example 24 in the evaluation results in Table 7, the adhesion and alkali release tests could not be performed on shrink PS, OPS, and CPS substrates because whitening of the substrate occurred during printing. [Industrial Applicability]

[0130] The resin composition of the present invention is useful as a material for preparing liquid compositions such as inks for forming alkali-releasable printed layers. The liquid composition of the present invention is also useful for inks, mediums, primers, overcoat varnishes, and the like for forming alkali-releasable printed layers. By providing a printed layer on a substrate made of a resin such as A-PET, HDPE, or LLDPE using the inks, mediums, primers, or overcoat varnishes of the present invention, a recyclable laminate can be easily obtained.

Claims

1. A resin composition used in a liquid composition for forming a removable printing layer on a substrate formed of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene, a (meth)acrylic resin (A) having an acid value of less than 25 mgKOH / g; a styrene-(meth)acrylic resin (B) having an acid value of 25 to 90 mgKOH / g; and a dispersion resin (C) having an acid value of 150 to 400 mg KOH / g, the total content of the styrene-(meth)acrylic resin (B) and the dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 10 to 30 mass %, the content of the dispersion resin (C) is 0.1 to 1.5 parts by mass relative to 1 part by mass of the styrene-(meth)acrylic resin (B), the total content of the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B), and the dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 65 to 100 mass%, The liquid composition contains a solvent including an alcohol-based solvent and an ester-based solvent, The resin composition, wherein the total content of the alcohol-based solvent and the ester-based solvent in the solvent is 90 to 100 mass %, and the mass ratio of the alcohol-based solvent to the ester-based solvent is 2.5:7.5 to 7:

3.

2. The resin composition according to claim 1, wherein the (meth)acrylic resin (A) has a glass transition temperature of 40 to 65°C.

3. 2. The resin composition according to claim 1, wherein the content of the (meth)acrylic resin (A) in the solid content of the liquid resin composition is 40 to 75 mass %.

4. 2. The resin composition according to claim 1, wherein the dispersing resin (C) is at least one selected from the group consisting of carboxylic acid-based resins and ammonium salt-based resins.

5. 2. The resin composition according to claim 1, further comprising silica having an average particle size of 1.0 to 8.0 μm.

6. The resin composition according to claim 1, further comprising a cellulose resin.

7. A liquid composition for forming a removable printing layer on a substrate formed of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene, a solvent including an alcohol-based solvent and an ester-based solvent; a printing composition for forming a non-detachable printing layer; The resin composition according to claim 1, The liquid composition has a total content of the alcohol-based solvent and the ester-based solvent in the solvent of 90 to 100 mass %, and a mass ratio of the alcohol-based solvent to the ester-based solvent of 2.5:7.5 to 7:

3.

8. A liquid composition for forming a removable printing layer on a substrate formed of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene, a (meth)acrylic resin (A) having an acid value of less than 25 mgKOH / g; a styrene-(meth)acrylic resin (B) having an acid value of 25 to 90 mgKOH / g; a dispersion resin (C) having an acid value of 150 to 400 mgKOH / g; a solvent including an alcohol-based solvent and an ester-based solvent, the total content of the styrene-(meth)acrylic resin (B) and the dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 10 to 30 mass %, the content of the dispersion resin (C) is 0.1 to 1.5 parts by mass relative to 1 part by mass of the styrene-(meth)acrylic resin (B), the total content of the (meth)acrylic resin (A), the styrene-(meth)acrylic resin (B), and the dispersion resin (C) in the solid content (excluding colorants such as pigments) of the liquid composition is 65 to 100 mass%, The liquid composition has a total content of the alcohol-based solvent and the ester-based solvent in the solvent of 90 to 100 mass %, and a mass ratio of the alcohol-based solvent to the ester-based solvent of 2.5:7.5 to 7:

3.

9. The liquid composition according to claim 7 or 8, wherein the alcohol-based solvent is at least one selected from the group consisting of isopropyl alcohol, methanol, ethanol, n-propanol, and n-butanol.

10. 9. The liquid composition according to claim 7, wherein the ester-based solvent is at least one selected from the group consisting of ethyl acetate, propyl acetate, and butyl acetate.

11. A liquid composition as described in claim 7 or 8, wherein when cellophane tape is applied to a portion of the surface of a printed layer formed by applying the liquid composition to the substrate and then quickly peeled off, the ratio of the area of ​​the peeled printed layer to the adhesive area of ​​the cellophane tape is less than 20%.

12. Use of the liquid composition according to claim 7 or 8 in a medium, a primer, an overcoat varnish, or an ink containing a colorant.

13. A medium, primer, overcoat varnish, or ink containing a coloring material, which is produced using the liquid composition according to claim 7 or 8.

14. A removable printing layer formed from the medium, primer, overcoat varnish, or ink containing a colorant according to claim 13, which is placed on a substrate formed from at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene.

15. a substrate formed of at least one resin selected from the group consisting of amorphous polyethylene terephthalate, high-density polyethylene, and linear low-density polyethylene; A laminate comprising the removable printed layer of claim 14 disposed on the substrate.

16. The laminate according to claim 15, which is a container or a lid material.

17. A method for removing a printed layer, comprising the step of contacting the printed layer of the laminate according to claim 15 with an alkaline aqueous solution to remove the printed layer from the substrate.

18. The method for removing a printed layer according to claim 17, further comprising the step of recovering the substrate from which the printed layer has been removed.

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